1. Field of the Invention
The present invention relates to the field of conveying bulk materials such as insulation, compost, mulch, peat moss, sawdust, corn, grains, etc. More particularly, the present invention relates to the field of leveling the top surface and hence controlling the depth of bulk material being transported on a conveyor and, by monitoring and controlling the depth of the bulk material on the conveyor and the speed of the conveyor, thereby monitoring and/or controlling the volume of bulk material being transported by the conveyor.
2. Description of Related Art
Bulk material such as insulation, compost, mulch, peat moss, sawdust, corn, grains, etc., is commonly transported on conveyors and, more particularly, belt conveyors. In connection therewith, it is often also desirable to measure and/or control the volume of the bulk material being transported by the conveyor. That is, it is often desirable to measure and/or control the volumetric feed rate at which the bulk material is being transported by the conveyor. It is known that by measuring and/or controlling the speed of the conveyor and the cross sectional area of the bulk material being transported by the conveyor, the volumetric feed rate can be determined and/or controlled.
The cross sectional area of the bulk material being transported is established and/or is bound by the width of the conveyor surface, the height of side walls which extend longitudinally along the conveyor and which maintain the bulk material on the conveyor, and the depth of the bulk material over the conveyor surface. Typically, the width of the conveyor surface and the height of the side walls are fixed, and the depth of the bulk material is controlled by leveling the top surface thereof to a desired height over the conveyor carrying surface. Of course, when leveling the top surface of the bulk material being transported on the conveyor, care must be taken to maintain a generally consistent density.
Prior bulk material leveling and volumetric measuring and/or feeding apparatus traditionally used a “gate” for essentially scraping excess bulk material and for thereby leveling the bulk material top surface at a desired height. For example, Lea U.S. Pat. No. 1,647,704 and Keeler U.S. Pat. No. 2,312,216 disclose volumetric measuring and feeding apparatus wherein granular bulk material is transported on a conveyor between side walls, and one or more gates are provided for leveling off the top surface of the bulk material as it is being transported via the conveyor. With the cross-sectional area of the bulk material and speed of the conveyor, the volumetric feed rate can be measured and/or controlled. However, depending on the quantity and overall height of bulk material behind the gates and the consistency of the bulk material, the density of the bulk material being transported will vary. Additionally, if an excess amount of bulk material is provided behind the gate, the weight thereof can sometimes cause the material to bind at the gate thereby causing it to plug up.
Sabi U.S. Pat. No. 3,199,793 discloses a gate like structure wherein knives are rotatably secured to a horizontal shaft which is located perpendicular to the conveyor longitudinal axis and over the bulk material being transported. As the bulk material approaches the rotating knives, the top surface is leveled off and excess bulk material is thrown backwardly. However, depending on the consistency of the material, the knives can compress the material and cause inconsistent densities. Moreover, in the event excess bulk material accumulates at a height above the knives horizontal shaft, the bulk material will be thrown forwardly instead.
Accordingly, an improved bulk material leveling and volumetric measuring and feeding apparatus is desired wherein the top surface of the bulk material being transported on a conveyor can be leveled at a desired height while maintaining the density of the bulk material thereunder generally consistent, and wherein the apparatus is generally not affected by excess bulk material that may accumulate behind the leveling apparatus.